An instant messaging system operates by sharing presence information among groups of users. For instance, the instant messaging system can communicate the presence-related status of a user to the user's contacts. The presence-related status may inform the contacts that the user is currently online, away, busy, and so forth. The instant messaging system can also convey personal information associated with the user. The personal information may reveal a personalized textual message associated with the user, a personalized display name, and so forth.
An instant messaging system typically manages the dissemination of presence information on an all-or-nothing basis. As shown in FIG. 1, such a system maintains a single collection of presence information 102 associated with a user 104. The single collection describes all aspects of a user's presence within the system. Further, the system maintains a single collection of permission information 106 that describes the users who are entitled to obtain the presence information 102, and a single collection of subscription information 108 that describes users 110 that have subscribed to receive notifications 112 based on the presence information 102. If so permitted by the permission information 102, a subscribing user can receive notifications 112 regarding all aspects of the single collection of presence information 102.
Instant messaging systems of the type described above may have various shortcomings which prevent effective utilization of presence information.